I train because I do track'n field, the field part: throwing events. They require some strength.
Because I want to see my limits and push them a little farther. I'm a peculiar thing at my gym, because few women or girls lift heavy weights with a goal for more strength. I'm already 42 and still trying to get stronger.
Because of health. They diagnosed articular rheumatism. Luckily, I didn't have to be pushed to the gym. In fact, the therapist I visited tried to talk me out of heavy weights, but I mostly ignore those advice. I go heavy as long as my body stays in one piece. Of course I don't train if I feel rheumatic pain. But I never had since I started taking that medicine.